1. Field of the Invention
The present invention relates to a coating and developing system for applying a liquid resist to a surface of a substrate, such as a semiconductor wafer or a LCD substrate, namely, a glass substrate for a liquid crystal display, to coat the surface with a resist film and developing the exposed resist film, and a coating and developing method.
2. Description of the Related Art
In a manufacturing process for manufacturing semiconductor devices or LCD panels, a resist pattern is formed on a substrate by a photolithographic process. The photolithographic process includes a series of steps of forming a resist film on a substrate, such as a semiconductor wafer (hereinafter, referred to simply as “wafer”) by applying a liquid resist to the surface of the substrate, exposing the resist film to light through a photomask, and developing the exposed resist film to form a desired resist pattern.
Generally, this photolithographic process is carried out by a resist pattern forming system built by combining an exposure system with a coating and developing system. FIG. 12 shows a known resist pattern forming system of this type disclosed in, for example, Patent document 1. Referring to FIG. 12, a carrier 10 holding a plurality of wafers W is delivered onto a carrier stage 11 installed in a carrier handling block 1A, and then a transfer arm 12 transfers the wafer W from the carrier 10 to a processing block 1B. The wafer W is delivered to a coating unit 13A installed in the processing block 1B. The coating unit 13A applies a liquid resist to a surface of the wafer W in a resist film. Subsequently, the wafer coated with the resist film is carried via an interface block 1C to an exposure system 1D.
The wafer W is returned to the processing block 1B after being subjected to an exposure process. A developing unit 13B subjects the wafer W to a developing process, and then the wafer W is returned to the carrier 10. Indicated at 14 (14a to 14c) in FIG. 12 are shelf units including a heating unit for processing a wafer by a predetermined heating process, a cooling unit for processing the wafer by a predetermined cooling process and a transfer stage. Each of the shelf units processes a wafer before or after the wafer is processed by the coating unit 13A and the developing unit 13B. Each of two carrying devices 15A and 15B installed in the processing block 1B carries a wafer W in the processing block 1B from one to another of modules in which the wafer W is to be placed, such as the coating unit 13A, the developing unit 13B and the shelf units 14a to 14c. Each of all the wafers W to be processed by the foregoing processes is carried to desired modules according to a carrying schedule specifying time points when the wafer W is to be carried to the modules.
Resist films of different types are formed in different coating mode, respectively. A first coating mode forms a resist film and antireflection films over and under the resist film, a second coating mode forms a resist film and an antireflection film over or under the resist film, and a third coating mode forms only a resist film. Therefore, in some cases, the units necessary for forming films, such as the coating unit, the heating unit and the cooling unit, processes wafers of different lots under different processing conditions. In such a case, a complex carrying program must be prepared for each type of the resist film when the coating unit, the heating unit and the cooling unit are installed in the same processing block because the different types of resist films are formed by using different units and are carried along different carrying paths. Since carrying programs to be produced according to the carrying schedule are originally complex, work for producing a carrying program for each of desired resist films is very complex and troublesome and such work is practically impossible.
When many units including the coating unit, the heating unit and the cooling unit are installed in the same processing block, the processing block is inevitably large and occupies a large area. A recent exposure system operates at a high throughput. Consequently, the coating and developing system is required to have a high processing ability corresponding to the throughput of the exposure system. However, the same carrying system operates to carry a wafer W to the coating unit for forming a resist film before the exposure process. Because the same carrying system operates to carry a wafer to an antireflection film forming unit for forming the antireflection film and to carry a wafer coated with an exposed resist film to the developing unit after exposure, it is difficult to operate the exposure system at a high throughput.
The inventors of the present invention have been making studies to develop a multilayer system including an area holding modules for processes preceding an exposure process and an area holding modules for containing modules for carrying out processes succeeding the exposure process disposed in a vertical arrangement to reduce load on carrying means, to improve carrying efficiency, to increase the throughput of a coating and developing system. Construction which disposes a coating area for a coating process and a developing area for a developing process in a vertical arrangement is disclosed in Patent document 2.
Although studies have been made on a multilayer system in which a coating area and a developing area are formed in different layers, respectively, to simplify constitution by reducing carrying systems, and to simplify a carrying program, nothing is mentioned in Patent document 2 about such improvements.
Patent document 1: JP 2004-193597 A
Patent document 2: Jpn. Pat. No. 3337677